Schwannomas are slow-growing, non-malignant tumors deriving from Schwann-lineage cells that develop along peripheral, spinal and cranial nerves. These tumors cause pain, sensory/motor dysfunction, and death through compression of peripheral nerves, the spinal cord, and/or the brain stem. Due to the suffering and debility associated with schwannomas and to the paucity of therapeutic options the FDA has indicated these tumors as orphan disease with major unmet medical need. We have developed a new therapeutic approach for schwannomas that involves intra-tumoral injection of an adeno-associated virus (AAV) vector carrying the pro-apoptotic gene caspase-1 (ICE) under a Schwann-cell specific promoter (P0); the vector is denoted AAV-P0-ICE. Our published pre-clinical studies have shown a remarkable ability of the AAV-P0-ICE vector to produce a prolonged reduction in tumor volume and tumor associated pain with no nerve damage. Following a pre-pre IND meeting with the FDA we have designed a development path to translate this therapy to clinical trials. The goal of this application is to perform the preclinicl experiments required for pre-IND submission. Specifically, we will need to define the precise dose range and structure of the vector that will be used in clinical trials. The dose range will be determined through a combination of toxicity and efficacy studies performed using mouse and human schwannomas established in the sciatic nerve of immunocompetent and immunocompromised mice, respectively. The vector structure will be established by comparing two vectors that differ in the species from which the promoter is derived - human versus rat. Further, clinical experience with AAV-based gene therapy demonstrates that humoral immunity to the viral vector can be a major limiting factor due to both neutralization of vector efficacy an vector-associated adverse effects. The studies described in this grant will address this issue by evaluating vector efficacy and toxicity in AAV-immune mice. This application is novel and innovative in that it utilizes the first viral vector that is restrictively expressed in Schwann-lieage cells, thus allowing targeting of schwannomas without apparent neurotoxicity. This therapeutic strategy is significantly less invasive than surgical resection, the current standard of care for schwannoma. Further, our pre-clinical data shows that AAV-P0-ICE induced schwannoma destruction leads to resolution of tumor-associated pain and does not cause any neural damage, the latter a common complication of surgical resection. Finally, to further support the development of this gene therapy we have submitted a patent application through our Institution and have established a licensing agreement with Abeona Therapeutics Inc. We thus believe that we have all the resources to develop AAV-P0-ICE for clinical testing in patients with schwannomas; the studies described in this application are essential to pursue our path to IND.